This invention relates to an improved electronic spelling machine and in particular to one havlng an enhanced ability to compare an input query word against a set of words stored in memory.
The utility of hand held electronic spelling machines is essentially in their ability to provide an appropriate list of suggested matches against a query word and to do so in a minimum of time. Utility is enhanced if the words presented are ranked in an order that presents the most likely word or spelling being sought.
One way of providing a fairly extensive list without overwhelming the user is to provide a list of candidates for the query word ranked in such a way that the most likely match is at the top of the list and the likelihood of the match being the one sought decreases as the user scrolls down the list. In this fashion, the user typically finds the word being sought immediately and only infrequently has to scroll further down the list of candidate words in order to find the appropriate word.
Closely related to this issue of providing a meaningful ranked list of words is the question of providing both typographic corrections and phonetic corrections. That is, a query word is put through a first process which provides a list of candidate words based on the assumption that there is a typographic error in the query word. The query word is also put through a different type of matching process in which the assumption is made that there are phonetic errors in the input word. For examp1e, spelling "bell" as either "ball" or as "bel" represents a typographic kind of error. By contrast, spelling "foreign" as "forun" is a phonetic type of error.
In any case it is known in the art to provide a correction pass which performs a phonetic type of correction and another correction pass which performs a typographic type of correction. These two passes provide two lists of candidate words, specifically a list of good phonetic matches and a list of good typographic matches.
Ranking the words in these two lists and merging them into a single list provides an enhanced result for a user in that on the average it materially decreases the time it takes the user to find the desired correctly spelled word.
Accordingly, the purpose of this invention is to provide a hand held electronic spelling device which provides a candidate list for a query word, which list merges the typographic correction list and the phonetic correction list and which orders the words in the merged list in a enhanced fashion in terms of value to the user.
A preferred embodiment of the invention employs the enhanced technique for encoding strings as disclosed in the above referenced, U.S. Pat. No. 5,113,340.
U.S. Pat. No. 4,490,811 dated Dec. 25, 1984 and entitled String Comparator Device System Circuit and Method discloses a string comparator technique of the sort with which the improvement of this invention operates. Applicant's references herein to a word similarity characteristic is to the string comparison function theta disclosed in the '811 patent. For convenience this function is called the theta function herein.